Organ builder Federico Acitores has used in the reconstruction of this organ some of the tubes installed in earlier periods by José Antonio Oria 859), Puignau y Olaciregui (1935) and Organería Española(1965).

In this case, 853 old tubes have been reused and 1.152 new tubes incorporated. It is a mechanical organ as regards both the notes and the registers. It has three manuals of 61 notes (Doh1-doh5) and a pedalboard of 30 notes (Doh1-fa3). The organ has a total of 32 real combinations.

With this instrument Federico Acitores has opted to continue with/ follow the symphonic tradition present in many organs in the Basque Country, thus following the style first established by French organ builders such as A. CavaillÈ-Coll and later followed by Basque organ-makers such as Aquilino Amezua, Lope Alberdi, Puignau y Olaciregui, Eguiguren, etc.

Another important characteristic of organ of the parish of San Nicol·s de Bari in Orio, one which distinguishes it from others, is its pedagogic function. It is an exceptional instrument in that it offers the possibility of seeing the inside, where all its vital parts and working mechanisms are easily accessible.

The design of the external case of the organ is both beautiful and innovative, with its structural lines and decoration bringing to mind the sea-faring spirit of the town of Orio.